如何更改特定元素的TextBox占位符文本颜色,而不是全局

Question

MSDN列出了样式和模板TextBox类在这里.我可以通过创建这样的ResourceDictionaryin 来覆盖这些主题资源App.xaml:

<Application.Resources>
    <ResourceDictionary>
        <ResourceDictionary.ThemeDictionaries>
            <ResourceDictionary x:Key="Default">
                <SolidColorBrush x:Key="TextBoxPlaceholderTextThemeBrush" Color="Yellow"/>
            </ResourceDictionary>
        </ResourceDictionary.ThemeDictionaries>
    </ResourceDictionary>
</Application.Resources>

但这会影响TextBox我的应用中的每一个.如何仅为特定元素设置此主题？

我试图把这个字典中Page.Resources,甚至TextBox.Resources对TextBox,我想将它应用到,但它不工作.

我真的不想重新定义Template刚改变这个属性.

---

编辑 Heena的答案很接近,但我还想为明暗主题设置不同的颜色,因为我的文本框具有透明的背景颜色.

我设法通过保持Foreground="{ThemeResource TextBoxPlaceholderTextThemeBrush}"作为其一部分来实现这一点Template(换句话说,模板完全是MSDN的默认模板),然后在页面资源中指定:

<Page.Resources>
    <ResourceDictionary.ThemeDictionaries>
        <ResourceDictionary x:Key="Light">
            <SolidColorBrush x:Key="TextBoxPlaceholderTextThemeBrush" Color="Blue"/>
        </ResourceDictionary>
        ...
    </ResourceDictionary.ThemeDictionaries>
</Page.Resources>

但现在这意味着我必须ControlTemplate在我的页面资源中为文本框设置一个巨大的样式设置器,这只是默认的默认复制品!

这是否与如何TextBoxPlaceholderTextThemeBrush从内部解决ControlTemplate？即它发现我的自定义主题词典的原因是因为它ControlTemplate是在同一资源字典中定义的？

应该怎么做？我应该只是将文本框子类化,以便将所有XAML移动到另一个文件(即使它仅用于一个文本框)？

Answer 1

假设您使用的是MSDN文本框样式

资源 从模板中的Contencontrol中删除前景属性<ContentControl Foreground="{ThemeResource TextBoxPlaceholderTextThemeBrush}"/>

<Page.Resources>
    <!--From MSDN : Default style for Windows.UI.Xaml.Controls.TextBox -->
    <Style x:Key="MsdnTextboxStyle" TargetType="TextBox">          
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="TextBox">
                 .....
                 .....
                <ContentControl x:Name="PlaceholderTextContentPresenter"
                              Grid.Row="1"                          
                              Margin="{TemplateBinding BorderThickness}"
                              Padding="{TemplateBinding Padding}"
                              IsTabStop="False"
                              Grid.ColumnSpan="2"
                              Content="{TemplateBinding PlaceholderText}" 
                              IsHitTestVisible="False"/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>           
</Page.Resources> 

XAML

 <StackPanel Orientation="Horizontal">
    <TextBox  PlaceholderText="PlaceholderText here..." Style="{StaticResource MsdnTextboxStyle}" Margin="20"  Foreground="Red" Height="30" Width="120">
        <TextBox.Resources>
            <Style TargetType="ContentControl">
                <Setter Property="Foreground" Value="Green"/>
            </Style>
        </TextBox.Resources>
    </TextBox>
    <TextBox  PlaceholderText="PlaceholderText here..." Style="{StaticResource MsdnTextboxStyle}" Margin="20"  Foreground="Red" Height="30" Width="120">
        <TextBox.Resources>
            <Style TargetType="ContentControl">
                <Setter Property="Foreground" Value="Red"/>
            </Style>
        </TextBox.Resources>
    </TextBox>
    <TextBox  PlaceholderText="PlaceholderText here..." Style="{StaticResource MsdnTextboxStyle}" Margin="20"  Foreground="Red" Height="30" Width="120">
        <TextBox.Resources>
            <Style TargetType="ContentControl">
                <Setter Property="Foreground" Value="Blue"/>
            </Style>
        </TextBox.Resources>
    </TextBox>
</StackPanel>

更新

资源

从模板中的Contencontrol中删除前景属性<ContentControl Foreground="{ThemeResource TextBoxPlaceholderTextThemeBrush}"/>

<Page.Resources>
    <ResourceDictionary>
        <ResourceDictionary.ThemeDictionaries>
            <ResourceDictionary x:Key="Default">
                <SolidColorBrush x:Key="ContentControlForeGround" Color="Red"></SolidColorBrush>
                <SolidColorBrush x:Key="ContentControlForeGround1" Color="Yellow"></SolidColorBrush>
            </ResourceDictionary>
            <ResourceDictionary x:Key="Light">
                <SolidColorBrush x:Key="ContentControlForeGround" Color="Blue"></SolidColorBrush>
                <SolidColorBrush x:Key="ContentControlForeGround1" Color="SkyBlue"></SolidColorBrush>
            </ResourceDictionary>
            <ResourceDictionary x:Key="Dark">
                <SolidColorBrush x:Key="ContentControlForeGround" Color="Green"></SolidColorBrush>
                <SolidColorBrush x:Key="ContentControlForeGround1" Color="Chocolate"></SolidColorBrush>
            </ResourceDictionary>
        </ResourceDictionary.ThemeDictionaries>
        <Style x:Key="TextBoxStyle1" TargetType="TextBox">
          .....
           <ContentControl x:Name="PlaceholderTextContentPresenter" Grid.ColumnSpan="2" Content="{TemplateBinding PlaceholderText}"  IsHitTestVisible="False" IsTabStop="False" Margin="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" Grid.Row="1"/>
           ......                                                       
        </Style>
    </ResourceDictionary>
</Page.Resources>

XAML

<StackPanel Orientation="Horizontal">
    <TextBox  Style="{StaticResource TextBoxStyle1}" PlaceholderText="PlaceholderText here..."  Margin="20"  Foreground="Red" Height="30" Width="170">
        <TextBox.Resources>
            <Style TargetType="ContentControl">
                <Setter Property="Foreground" Value="{StaticResource ContentControlForeGround}"></Setter>
            </Style>
        </TextBox.Resources>
    </TextBox>
    <TextBox  Style="{StaticResource TextBoxStyle1}" PlaceholderText="PlaceholderText here..."  Margin="20"  Foreground="Red" Height="30" Width="170">
        <TextBox.Resources>
            <Style TargetType="ContentControl">
                <Setter Property="Foreground" Value="{StaticResource ContentControlForeGround1}"></Setter>
            </Style>
        </TextBox.Resources>
    </TextBox>
</StackPanel>